Bart and co. gather around the Springfield lemon tree to bask in the citrus-y goodness. A few metres away, just over the Springfield/Shelbyville border, some hoodlums gather and the insults fly:

Shelbyville Kid: You're a garbage man.
Bart: I know you are, but what am I?
Shelbyville Kid: A garbage man.
Bart: I know you are, but what am I?
Shelbyville Kid: A garbage man.
Bart: I know you are, but what am I?
Shelbyville Kid: A garbage man.
Bart: Takes one to know one!